11 replies so far

My choice is to use a 3/8” tenon on 3/4” material. The width will be determined by the width of your frames. Leave enough wood on the end, so that you don’t have a weak spot that will break. It’s a good idea to leave the excess, dog ears, on the end of your frame pieces, until you’re all glued up, then cut to length.

My understanding is the tenon should be 1/3 the thickness of the stock being mortised. In your case, I would go with 1/4” as DaveR recommends. As the mortise gets bigger, it weakens the mortised stock. Having said that, for face frames I doubt if it makes much difference since it will be attached to the body of the project where it will get most of its strength. It’s not a load bearing joint.

-- Failure is the road to success if you learn to learn from your mistakes - Vince, Greenville, SC

I agree with DaveR and araldite. But I also wonder why you chose loose tenons for the joinery. Why not biscuits? Pocket screws? araldite is correct when he said it is not a load bearing joint and loose tenons would be overkill. But, having said that, it is good experience, will make a strong frame, and the project will be an heirloom. I am anxious to see this in the projects section. Good luck

Not saying anyone is right or wrong. I guess I went to an older school of thought than most of these guys.The “old school” says the sides of the mortise added together should equal the thickness of the mortise, other wise you have a weak tenon. So that makes the tenon half the thickness of the piece, not a third. It probably doesn’t make any difference on face frames. Once they’re attached to the case they don’t have any stress on them anyway. You just might want to do some more research into joinery layout before you build anything that is going to be stressing the joints. That’s my old $0.02 worth.

For a face frame, there is no reason to have a m/t joint more than 1/3 of the total thickness. In most cases when you make a m/t joint in cabinet door, your mortise will be the same as the groove for the panel which is 1/4”.